NONSTATIONARY HEAT EXCHANGE IN THE TRACHEA OF HUMAN LUNGSK. M. Aref'ev, E. D. Fedotovich, and A. A. Khrushchenko UDC 536.24 Calculations of the heat exchange in the trachea of human lungs have been carried out. Unlike other works in this field, in the present work the authors have taken account of the nonstationarity of the processes, which is related to the alternation of inhalations and exhalations and the variability of the air flow rates. Nonstationary changes in the temperature of trachea walls in quiet breathing have been calculated in different cases. St. Petersburg State Polytechnic University, St. Petersburg, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 76, No. 4, pp. 128-133, July-August, 2003. Original article submitted November 12, 2002.